Breeding Sugar Beets For Better Resistance To Curly Top Virus

A new sugar beet germplasm breeding line developed by U.S. Department of Agriculture (USDA) scientists could usher in new varieties of the sugar crop that can better withstand the sugar beet curly top virus.
Small insects called “beet leafhoppers” transmit the virus, wreaking cellular havoc that can result in yellow, inwardly curled leaves, stunted growth and other tell-tale signs. Severe outbreaks of curly top disease can reduce sugar beet yields by up to 30%.
Spraying insecticides can prevent leafhoppers from transmitting the virus, but the preferred approach is to plant sugar beet varieties that naturally resist the pathogen, notes Imad Eujayl, a molecular biologist with Agricultural Research Service (ARS) in Kimberly, Idaho.
Sugar beet leafhoppers - ARS image
Figure 1. Sugar beet leafhoppers. (Source: USDA ARS)
Together with ARS plant pathologist Carl Strausbaugh and members of the Beet Sugar Development Foundation, Eujayl developed and released new germplasm line KDH13. The work was part of an ongoing sugar beet improvement program at the ARS Northwest Irrigation and Soils Research Lab in Kimberly.
KDH13 resulted from “gynogenesis,” a tissue-culture technique in which the new sugar beet line began from the regenerated egg-cell tissue of a single, unfertilized female parent plant known to be resistant to the virus. In greenhouse and nursery tests, mature plants of KDH13 outperformed Hilleshog PM90, a top resistant cultivar used for comparison.
Curly top virus
Figure 2. Yellow, inwardly curled leaves, stunted growth and other signs of curly top virus in sugarbeet.
Genetically sequenced since, the new germplasm line is available to beet breeders and seed companies as a source of resistance genes for breeding into commercial varieties to improve tolerance to the virus, according to Eujayl.
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Strip Tillage in Sugarbeet Rotations

There were many growers considering strip tillage as an alternative to full width tillage in 2008. High fuel and fertilizer prices were strong influences in peaking grower interest in strip tillage. Because of the volatility of fuel and fertilizer prices in recent months, strip tillage is still a practice of interest to growers. Sugarbeet producers who farm silty and sandy soil types prone to wind erosion were among those particularly interested in strip tillage. A wind storm occurred on May 17th, 2008, affecting thousands of acres in the Red River Valley and causing affected growers to reconsider the importance of reduced tillage, cover crops, and other practices that reduce susceptibility to wind erosion. Additionally, autosteer technology is becoming common on many sugarbeet farms in ND and MN and is particularly beneficial in strip tillage systems because it assures that growers can plant seeds directly into the middle of the strips that were made the preceding fall or earlier in the spring. Roundup Ready sugarbeet varieties reduce grower dependence on cultivation as a weed control method, which also makes weed control in strip tillage more manageable. Because sugarbeet growers are also soybean, corn, and wheat growers, we included these other commonly grown crops to determine their productivity potential in strip tillage cropping rotations with 22-inch row spacings. 

In strip-tillage, narrow strips, usually 7-10 inches wide, are tilled and then planted with standard planting equipment, often modified with row cleaners. The area between rows remains undisturbed throughout the growing season. Strip-tillage is optimal in well-drained soils prone to wind erosion. Additionally, strip-tillage allows the cultivated strips of soil to warm up and dry faster than no-till systems in the spring for early-seeded crops. During dry periods, the inter-row areas retain moisture, which is available for crop use. This is a particular benefit in the spring, when dry soil conditions may result in reduced or uneven seedling emergence and consequently poorer stand
establishment. These properties of strip-tillage make this method well-suited for the soils of the RRV, which are frequently cold and wet early in the planting season and are also highly susceptible to wind and flood-water induced soil erosion in the spring. Advantages that growers will experience directly by implementing strip-tillage are reduced fuel expenditures, less labor, time and machinery use, improved soil structure, and the potential for conservation payments through federal programs and carbon credit trading boards.

Many areas of the U.S. Corn Belt utilize strip-tillage for corn production and it has been shown to result in corn yields similar to conventional tillage while also providing the benefits of wind protection and accurate placement of N, P, and K beneath the soil surface (unlike no-till). Additionally, strip-tillage has the potential to enhance use of P by optimizing placement, which may result in recommendations for reduced P fertilizer rates for strip tillage production in ND and MN.

Economically, strip tillage allows for fuel savings because primary and secondary tillage operations with chisel plow, field cultivators, etc. are eliminated. Strip tillage also eliminates additional fuel inputs associated with fertilizer application and weed cultivations in conventional tillage systems. Labor costs may be reduced in association with fewer field operations. Fertilizer savings may be realized if fertilizer banding increases N and/or P uptake efficiency, allowing a fertilizer rate reduction. However, an early season chemical burn-down operation unneeded in full width tillage systems may add additional cost to strip tillage systems. Planting and harvesting
operations are the same for strip till and conventional till systems. Converting to strip-till production requires investment in new equipment associated with equipment cost, insurance, and storage… <more>


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